The present disclosure is generally related to medical systems, devices, and methods for treating a glaucomatous eye. In some embodiments, a handheld treatment device is configured for delivering therapeutic light toward a target tissue. The handheld treatment device may be provided with a replaceable distal contact tip. In further embodiments, ophthalmic treatment systems may be provided that include a treatment device for delivering therapeutic light toward a target tissue and a treatment guide for placement against an eye of a patient that may interface with the distal end of the treatment device to align the device with one or more treatment locations about the eye of the patient.
Glaucoma is a leading cause of blindness. Glaucoma involves the loss of retinal ganglion cells in a characteristic pattern of optic neuropathy. Untreated glaucoma can lead to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness. The loss of visual field due to glaucoma often occurs gradually over a long time and may only be recognized when the loss is already quite advanced. Once lost, this damaged visual field can never be recovered.
Elevated intraocular pressure (IOP) is a significant risk factor for developing glaucoma. IOP is a function of production of aqueous humor by the ciliary body of the eye and its drainage through the trabecular meshwork and all other outflow pathways including the uveoscleral pathway. Aqueous humor is a complex mixture of electrolytes, organics solutes, and other proteins that supply nutrients to the non-vascularized tissues of the anterior chamber of the eye. It flows from the ciliary bodies into the posterior chamber, bounded posteriorly by the lens and the ciliary zonule and bounded anteriorly by the iris. Aqueous humor then flows through the pupil of the iris into the anterior chamber, bounded posteriorly by the iris and anteriorly by the cornea. In the conventional aqueous humor outflow path, the trabecular meshwork drains aqueous humor from the anterior chamber via Schlemm's canal into scleral plexuses and the general blood circulation. In open angle glaucoma there is reduced flow through the trabecular meshwork. In angle closure glaucoma, the iris is pushed forward against the trabecular meshwork, preventing the egress of fluid.
Uveoscleral outflow is a non-conventional pathway that is gaining importance in the management of glaucoma. In uveoscleral outflow, aqueous humor enters the ciliary muscles from the anterior chamber and exits through the supraciliary space and across the anterior or posterior sclera. Uveoscleral outflow may contribute significantly to total aqueous humor outflow.
Currently, glaucoma therapies aim to reduce IOP by either limiting the production of aqueous humor or by increasing the outflow of aqueous humor. Medications such as beta-blockers, carbonic anhydrase inhibitors, etc., are used as the primary treatment to reduce the production of aqueous humor. Medications may also be used as the primary therapy to increase the outflow of the aqueous humor. Miotic and cholinergic drugs increase the trabecular outflow, while prostaglandin drugs, for example, Latanoprost and Bimatoprost, increase the uveoscleral outflow. These drugs, however, are expensive and have undesirable side effects, which can cause compliance-dependent problems over time.
Surgery may also be used to increase the outflow or to lower the production of aqueous humor. Laser trabeculoplasty is the application of a laser beam over areas of the trabecular meshwork to increase the outflow. Cyclocryotherapy and laser cyclophotocoagulation are surgical attempts to lower the production of aqueous humor by the ciliary processes. Although they may be effective, these destructive surgical interventions are normally used as a last resource in the management of glaucoma due to the risk of the severe complication of phthisis bulbi. Other adverse side effects of cyclodestructive surgical procedures may include ocular hypotony and inflammation of the anterior eye segment, which may be associated with an increased incidence of macula complications. Still other adverse side effects include transient hyphaema and exudates in the anterior chamber, uveitis, visual loss, and necrotizing scleritis.
In laser transscleral cyclophotocoagulation, high intensity continuous wave (CW) infrared laser energy is directed through selected portions of the pars plicata region to the ciliary body, structures under the scleral layers and the overlying conjunctiva. Selected portions of the ciliary body and related processes are permanently destroyed, thereby decreasing the overall production of aqueous humor. Laser energy may be directed through air to a patient seated at a special slit lamp. Alternatively, laser energy may be delivered through the use of fiber optic handpieces placed in contact with the patient's eyeball. In both laser energy delivery methods, however, accurately and repeatedly directing a laser beam to a subsurface non-visible target such as the ciliary body can be challenging for a surgeon.
While the prior systems, methods, and devices have provided advancements in the art, further improvements are desired.